Over hundreds of thousands of years, the Earth's rotation slows down by 1 second every 40,000 years, due to tidal friction (the oceanic bulge raised by the tides rubs against the bottom of shallow seas and coastal areas).
Over gazillion years, Earth's orbit moves away from the Sun by some fraction of an inch every million years, because the Sun turns mass into energy (e = m c^2); the Sun loses 4.5 million tonnes of mass every second (which, when compared to the Sun's total mass, is negligible).
On a year-to-year basis, the Earth's rotation may accelerate OR decelerate as earthquakes redistribute the mass around it rotation axis. For example, an earthquake that lifts an important section of a plate will slow down the rotation. However, one that lowers a hunk of mass will acceleration rotation.
Strong evaporation of the oceans, bringing rain to mountain tops, will slow down rotation. Heavy melting of mountain ice (allowing water to run down to oceans) will accelerate rotation.
Every year, Earth's mean distance from the Sun can change by as much as 500 km, due to the gravitational effect of other planets (mostly Jupiter and Saturn). This changes, ever so slightly, the real length of the sidereal year.
And so on...